The invention relates to perpendicular magnetic recording heads, and more particularly, to a perpendicular magnetic recording head with a laminated main write pole.
Magnetic recording heads have utility for use in a magnetic disc drive storage system. Most magnetic recording heads used in such systems today are xe2x80x9clongitudinalxe2x80x9d magnetic recording heads. Longitudinal magnetic recording in its conventional form has been projected to suffer from superparamagnetic instabilities at densities above approximately 40 Gbit/in2. It is believed that reducing or changing the bit cell aspect ratio will extend this limit up to approximately 100 Gbit/in2. However, for recording densities above 100 Gbit/in2, different approaches will likely be necessary to overcome the limitations of longitudinal magnetic recording.
An alternative to longitudinal recording is xe2x80x9cperpendicularxe2x80x9d magnetic recording. Perpendicular magnetic recording is believed to have the capability of extending recording densities well beyond the limits of longitudinal magnetic recording. Perpendicular magnetic recording heads for use with a perpendicular magnetic storage medium may include a pair of magnetically coupled poles, including a main write pole having a small bottom surface area and a flux return pole having a larger bottom surface area. A coil having a plurality of turns is located adjacent to the main write pole for inducing a magnetic field between that pole and a soft underlayer of the storage media. The soft underlayer is located below the hard magnetic recording layer of the storage media and enhances the amplitude of the field produced by the main pole. This, in turn, allows the use of storage media with higher coercive force, consequently, more stable bits can be stored in the media. In the recording process, an electrical current in the coil energizes the main pole, which produces a magnetic field. The image of this field is produced in the soft underlayer to enhance the field strength produced in the magnetic media. The flux density that diverges from the tip into the soft underlayer returns through the return flux pole. The return pole is located sufficiently far apart from the main write pole such that the material of the return pole does not affect the magnetic flux of the main write pole, which is directed vertically into the hard layer and the soft underlayer of the storage media.
In selecting a material to form the main write pole, it is desirable to have a material that exhibits a large or high saturation magnetization (4xcfx80Ms), a low coercivity, and a well-defined uniaxial anisotropy. These factors are particularly important for a perpendicular magnetic recording head which utilizes a deep gap field to perform a write operation, as opposed to a fringing field utilized by a longitudinal magnetic recording head.
For example, one of the highest saturation magnetizations at room temperature is if exhibited by the material Fe65Co35 which has a saturation magnetization value of approximately 2.4 T. However, certain properties exhibited by this material prevent it from being suitable for use as a main write pole material. Specifically, this material is not sufficiently magnetically soft or uniaxial, therefore, it has a nearly zero permeability which results in an inefficient write head. The lack of uniaxiality or magnetic softness is a direct result of the relatively large value of magnetocrystalline anisotropy exhibited by many of the high moment FeCo alloys. However, because of the high saturation magnetization exhibited by these materials, it would be desirable to use these materials to form the main write pole.
There is identified a need for an improved main write pole of a perpendicular magnetic recording head that overcomes limitations, disadvantages, and/or shortcomings of known main write poles.
Embodiments of the invention meet the identified need, as well as other needs, as will be more fully understood following a review of the specification and drawings.
In accordance with an aspect of the invention, a main write pole for a perpendicular magnetic recording head comprises a first magnetic layer having a high saturation magnetization, a second magnetic layer having a high saturation magnetization, and a non-magnetic interlayer positioned between the first magnetic layer and the second magnetic layer. The first and second magnetic layers comprise FexCoy, wherein 40xe2x89xa6xxe2x89xa690 and 10xe2x89xa6yxe2x89xa660.
In accordance with an additional aspect of the invention, a perpendicular magnetic recording head comprises a main write pole and a return pole magnetically coupled to the main write pole. The main write pole comprises a first magnetic layer having a saturation magnetization greater than about 1.8 T, a second magnetic layer having a saturation magnetization greater than about 1.8 T, and a non-magnetic interlayer positioned between the first magnetic layer and the second magnetic layer.
In accordance with an additional aspect of the invention, a perpendicular magnetic recording head comprises a main write pole and a return pole magnetically coupled to the main write pole. The main write pole comprises a first magnetic layer comprising FexCoy, wherein 40xe2x89xa6xxe2x89xa690 and 10xe2x89xa6yxe2x89xa660, a second magnetic layer comprising FexCoy, wherein 40xe2x89xa6xxe2x89xa690 and 10xe2x89xa6yxe2x89xa660, and a non-magnetic interlayer positioned therebetween.
In accordance with yet another aspect of the invention, a magnetic disc drive storage system comprises a housing, a perpendicular magnetic recording medium positioned in the housing, and a perpendicular magnetic recording head mounted in the housing adjacent the magnetic recording medium. The magnetic recording head includes a main write pole and a return pole magnetically coupled to the write pole. The main write pole includes a first magnetic layer having a high saturation magnetization, a second magnetic layer having a high saturation magnetization, and a non-magnetic interlayer positioned between the first magnetic layer and the second magnetic layer.